To investigate the biologic effects of preservative-free artificial tear drops on cultured human corneal epithelial cells in vitro .

Efficacies of the preservative-free artificial tear drops-Kynex®, Hyalein Mini 0.3%®, and Refresh Plus®-were evaluated using the MTT assay. Cell damage was determined using the lactate dehydrogenase (LDH) assay. Cellular proliferation was determined using a migration and wound-healing assay. The ingredients of the drugs were analyzed. Apoptotic response was evaluated with flow cytometric analysis.

Metabolic activity of the corneal epithelial cells showed similar activity to that of the control. Cellular migration and proliferation also were not significantly different between the preservative-free artificial tear drop groups and the control. The LDH titers tended to increase for up to 24 hours after exposure to the preservative-free artificial tear drops, but there was no significant difference in LDH titers between the control groups and the artificial tear drop-treated groups. Apoptosis and necrosis were observed using flow cytometry at 24 hours in all groups. The electrolyte levels, pHs and osmolarities of the three drugs were not significantly different.

The clinically available preservative-free artificial tear drops Kynex®, Hyalein Mini 0.3%®, and Refresh Plus® had no significant toxic effects on corneal epithelial cells and thus can be used safely.